Edge-forming apparatus and method



Aug- 22, 1967 R. D. FOLLRATH 3,336,778

EDGE-FORMING APPARATUS AND METHOD 1 N n o N) N L0 N Q INVENTOR.

RICHARD D. FOLLRATH v )m BY mi #fz/'74' R. D. FOLLRATH 3,336,778

EDGE-FORMING APPARATUS AND METHOD Aug. 22, 1967 3 Sheets-Sheet Filed June 1964 m .mi

INVENTOR.

RICHARD D. FOLLRATH R. D. FOLLRATH EDGE-FORMING APPARATUS AND METHOD Aug. 22, 1967 3 Sheets-Sheet 5 Filed June 8, 1964 INVENTOR RICHARD D. FOLLRATH United States Patent O ware Filed June 8, 1964, Ser. No. 373,159 Claims. (Cl. 72-203) My invention relates to edge-forming methods and apparatus and particularly to rolling rounded edges on electrical conductor strip.

In the manufacture of electrical apparatus employing induction coils, there has been an increasing commercial interest in forming such coils from flat strip conductors instead of using round or square magnet wire. When used in such coils the strip may be enamelled, it may merely be interleaved with a layer of insulating material such as paper, Mylar or other suitable dielectric, or the two insulating means may be combined.

The most troublesome portions of magnet strip coils are their edge portions, for, when the strip is formed, usually by slitting it yfrom wide sheets, the edges are likely to be burred and sharp-cornered. For enamelled strip, the edge is the most di'icult to cover uniformly with an insulating coat; the electrical stresses are most concentrated at the edges; and in the Wound coils the edges remain exposed compared to the llat surfaces, each of whlich is protected by an adjacent outer winding of the co1 I have found that the best magnet strip conductor is one in which the edge is fully formed, that is, the edge is rounded in a semicircle or similar curve that is tangent to, or blends continuously with, the at sides of the strip. This is opposed to a mere rounding or breaking of the corners. However, when attempts were made to manufacture strip conductor on a commercial scale it was found that none of the known apparatus was capable of producing an acceptable product. The reasons for this may be that magnet strip is relatively wide and thin compared to strip that has previously been made with a rounded edge. The metals are soft, usually copper or aluminum, and cannot withstand much end thrust, and the required degree of reliability is very great.

In the practice of my invention I propose to economically produce electrical strip with fully formed edges.

I further propose to produce strip which is precisely dimensioned within close tolerances.

I further propose to produce strip in a process with high reliability.

The edges of metallic strip can be rounded by electro-y lytic erosion, grinding or skiving, etc., but I have found that edge rolling the strip is the most reliable and satis-` factory process. In edge rolling, however, the strip is subjected to very high buckling pressures that tend not only to buckle the sheet but also to thicken the strip section adjacent to the edge rolls. I have found that known types of edge rolls do not perform satisfactorily, but that if the groove is cut in the roll in a manner not, to my knowledge, heretofore suggested, the resulting edge is fully formed and is free from irregularities, and the strip is free from pronounced thickening adjacent to the rolled edges. Whenever some slight thickening does occur it can be readily removed by a single pass through horizontal rolls mounted downstream of the edging rolls. I have discovered that an essential element for rolling satisfactory edge contours on electrical magnet strip is a very deep groove in the edging roll. This groove should have a depth at least 21/2V times the thickness of the strip, and the depth may be as much as 8 times this thickness. The side walls forming the groove should be substantially straight in radial section and should taper outwardly only slightly so that the opening of the groove is no more than one or two mils wider than the groove at the beginning of the ear bottom contour blending into the sidewalls. The grooves have depth to width ratios of at least 2.5 and the 3,336,778 Patented Aug. 22, 1967 bottom curvature. This curvature at the base of the groove is preferably semicircular or parabolic and should blend into the side walls Without any sharp discontinuity.

Great precision is, of course, required of the grooves cut in the edging rolls, and it is preferable to grind in the grooves after the rolls are hardened. To control the shape and dimensions of the groove contour it is advisable to make wax or lead impressions of the groove which can be checked under a microscope.

I have found that a plurality of passes through my edging rolls are usually necessary to achieve a fully-formed edge. This is conveniently accomplished iby mounting a plurality, such as six rolls per edge, in series. Before passing through these rolls the strip is advantageously treated by brushing the four corners of the edges to remove burrs and break the sharpness of the corners. Following this, and prior to entering the above-described grooved edging rolls, I further preform the edges by means of V-notched rolls. Here the notch has a angle and the same roll can be used for strips of widely different gage. Each groove of the grooved'rolls, however, can be used for only one gage of strip, but a plurality of different sized grooves can be cut into one roll, and the latter can be used yfor different strip gages by merely changing its Vertical position.

The required precision of edge rolling is greater than theusual precision of slitting wide strips so that I prefer not to set my rolls in Xed positions and rely on the uniformity of the width of thestrip to seat it properly in the notch and grooves of the rolls. Rather, I mount one, or both, of each opposing pair of rolls to slide in the plane of the advancing strip, and I urge the rolls against the strip by the application of a constant force. As an urging means I have found it advantageous to use air or hydraulic cylinders. When this is done the magnitude of the force can easily be controlled by regulating the pressure. I have discovered that an apparatus having all the rolls on one side of the strip slidably mounted and the rolls on the opposite side fXedly mounted is satisfactory for running strip that is perfectly straight. When there is a possibility of the strip being cambered, however, as is frequently the case in commercial practice, I prefer to mount all the rolls slidably.

My apparatus for edge-forming metallic strip comprises means for paying off the strip and means for advancing it through the apparatus. The strip has square or angular corners, bein-g most commonly slit from a wide sheet, and my apparatus comprises brushes mounted in the path of advance of the strip rotating against the corners so as to deburr and break them. It also comprises V-notched rolls mounted to rotate on axes normal to the advance of the strip wtih circumferential V-notches positioned to engage the edges of the strip and further break the corners. Edgeforming rolls are mounted in my apparatus also to rotate on axes normal to the advance of the strip. There are means mounting the V-notched and edge-forming rolls movably against the strip, and means, such as air cylinders, urging the movably mounted rolls against the strip. My

edging roll for forming the edge of metallic strip has atV least one circumferential edge-forming groove with side walls substantially straight in radial section, and a curvilinopenings of the sidewalls forming the grooves do not exceed their separation at the circumferential lines where the bottom contour blends in, by more than about 2 mils.

A more thorough understanding of my invention can be gained from the appended drawing.

In the drawing: FIGURE 1 shows a side view of an edging roll made to my invention.

FIGURE 2 shows an enlarged view of a groove in the roll of FIGURE 1.

-FIGURE 3 shows an enlarged view of a V-notch in a roll used in my apparatus.

FIGURE 4 shows a side view of the apparatus of my invention.

FIGURE 5 shows a side view, partly in section, of the length 5 5 of FIGURE 4.

FIGURE 6 shows a plan view of the apparatus of FIGURE 5.

FIGURE 7 shows a front view of an element of the apparatus of FIGURE 4.

With reference to FIGURE 1 a cylindrical roll 11, rotatable on a vertical axis, is ground or cut with a plurality of circumferential grooves 12, 14 of different widths to fit different gages of strip. Although I have shown two different sized grooves in my roll 11 it will be understood that the roll may have a single groove or it may have a plurality of grooves all the same size. In the latter case the grooves can be used consecutively as they become worn. In IFIGURE 2 the groove 12 is shown on an enlarged scale and is seen to be formed of straight side walls 16, 17 and a curvilinear bottom contour 18. The contour 18 is semicircular but it will be understood that other contours may also be used within the scope of my invention. The curvilinear bottom portion 18 is tangential to the walls 16, 17 at circumferential lines 19, 20, respectively, and these -lines mark the beginning of the curved portion f the groove 12. Between the lines 19, 20 the groove 12 has a width w` which is from 0 to about 1 mil thicker than the stock to be edge rolled, and the walls 16, 17 taper outwardly so that a width x at the opening of the groove is greater than the width w. The difference between the opening and the bottom widths is not great, however, being only about 1 or, at most about 2 mils.

The groove 12 has a depth d and the ratio d/ w constitutes an important element of my invention. In the embodiment of FIGURE 2 d/w is equal to 3 and I have found that it should in no case be less than 21/2 for the proper practice of my invention.

The grooved rolls such as the roll 11 are mounted on a bench 21 in an apparatus indicated generally by the numeral 22 (FIGURE 4). This apparatus comprises a pay-off stand 23 supporting a coil 24 of metallic strip 26 which is payed over a rubber-surfaced guide roll 27 to establish its elevation in passing through my apparatus. The strip 26 then passes under two brushes 28, 29 (FIGURE 6) and over two brushes 30, 31 which deburr the corners of the strip and also break the sharp angles of the corners. I prefer to employ fiber brushes such as the brushes made by the Osborn Manufacturing Company and sold under the trademark Fascut. The preferred brushes are 8 inches in -diameter and 1/2 inch wide and are rotated at high speed such as 3400 r.p.m., but it will be understood that it has been known to deburr metal edges by brushing and other known types of brushes and speeds of rotation can be used within the scope of my invention. A further description of the mounting of the brushes 28-31 is given hereinbelow with reference to a detailed description of FIGURES and 6. On leaving the area of the brushes 30, 31 the strip 26 passes between two notched rolls 33, 34 in each of which is cut a V-notch 36 (FIGURE 3) formed by walls 37, 38 which are straight in radial section and meet at an angle of about 90. By means of the notches 36 I preform the edges of my' strip in preparation for full-forming by the grooved rolls 11. Although I have shown a 90 notch 36 in my roll 33 (there is, of course, a similar notch in the roll 34), I do not wish to be limited to this angle. It is also conceivable that my apparatus would be operable without the rolls 33, 34. Omission of these rolls would, however, require additional rolls 11 to complete the edge forming in one pass. The rolls 33, 34 can be used with a wide range of metal gages whereas each of the rolls 11 must be changed, either by substituting another roll or by reversing the roll to position the other groove in line with the strip, whenever a different gage of strip is run through the apparatus. My apparatus 22 has six pairs of grooved rolls 11 mounted in tandem, and upon leaving the furthest downstream of these rolls with edges of the strip 26 fully formed, the strip passes over a second rubber-surfaced guide roll 39 and through a pair of flat rolls 41, 42 set at the precise strip gage. These fiat rolls eliminate any slight thickening of the strip section. As stated hereinabove, it is a feature of my invention that the shape of the grooves cut in the rolls 11 serves to minimize thickening of the edges and the presence of the flat rolls 41, l42 are in the nature of a precaution to correct for any slight edge growth that may result. Upon leaving the fiat rolls 41, 42 the strip 26 enters a known type of degreasing.

tank 43 and dryer 44 from which it is taken up into a coil 46 mounted in a stand 47 and driven by a motor 48 through a chain 49.

Referring particularly to FIGURES 5, 6 and 7 the brushes 28-31 are mounted on respective shafts 51-54 of motors 56-59 mounted, in turn, on respective sliding platforms 61-64 which slide in pairs of greased rails 66-66, 67-67.

Screw blocks 68 are fastened to the bottom of each of the platforms 61-64. The screw blocks are threaded onto double pitch screws 69, 70 turned by respective hand cranks 71, 72. By turning the cranks 71, 72 the positions of the brushes 28-31 can be adjusted horizontally to accommodate strips 26 of different Widths.

The V-notched rolls 33, 34 are similarly mounted on sliding platforms 73, 74 slidable in rails 75-75 that can be adjusted by means of a crank 76, screw 77, and screw blocks 78. However, as can best be seen in FIGURE 5 the rolls 33, 34 are mounted to slide relative to the platforms 73, 74 so that they can follow slight variations in the width of the strip when urged by air cylinders 79a, 79h. These may be true variations or effective variations due to a slight camber in the strip. For this purpose the rolls 33, 34 are mounted on second platforms 81a, 81b slidable on the respective platforms 73, 74 within the gibs 82-82. Pistons 83a and 83b of the cylinders 79a and 791; urge the platforms 81a and 8111 toward each other with a constant, predetermined force. The grooved edging rolls 11 are similarly mounted except that each of the slidable platforms mounts two rolls instead of one. Thus for mounting the first four grooved rolls downstream of the V- notched rolls, platforms 84, 85 are slidable in rails 86-86 and are adjustable by means of a hand crank 87, screw 88 and screw .blocks 89. Second platforms 91a and 91b slidably support opposing yokes 92a, 92b for the rolls 11 and are urged toward each other 'by air cylinders 93a, 93b. The mounting of the additional 8 grooved rolls urged by air cylinders 94a, 94b, 95a, 95b are substantially identical. It will be understood that although I have preferred, in the illustrated embodiments of my invention to apply a force to only one of each pair of opposing rolls all the rolls might be mounted to continuously follow variations in the width of the strip within the scope of my invention. The cylinders 79a, 79b, 93a, 93b, 94a, 94b, 95a, 95b are fed by air lines 96-99 controlled by regulators 101-104 to supply a constant air pressure as indicated by air gages 106-109. This pressure can be changed according to the thickness and hardness or toughness of the strip being processed.

During contact with the edging rolls, the strip is supported and held flat `by means of a shoe assembly shown in FIGURE 7. The shoes have been omitted from the other figures for the sake of clarity. The assembly 115 comprises a lower shoe 114 fixed to the rail 75 by means of posts 116, 117 and an upper shoe 1,18 fixed to a pair of rods 119 of which only one is visible in the drawing. The other rod and its supporting structure is symmetrically located on the other side of the platforms 84, 85 as seen in FIGURE 7. The rod 119 shown in the drawing is supported on brackets 121, 122 and urged against the said brackets by compression springs 123, 124. The rod 119 is fastened to the bracket 121 by means of a hinge 126, and to the bracket 122 by means of a latch 127. This arrangement permits the upper shoe to be lifted out of the way for threading my apparatus. Although I have shown the shoe assembly associated with the platforms 84, 85, it will be understood that a similar shoe assembly is used -to keep the strip flat between each set of edging rolls.

I have invented a new and useful apparatus and method for which I desire an award of Letters Patent.

I claim:

1. The method of edge-forming electrical conductor strip comprising the steps of:

(A) brushing the corners of said strip to deburr the same and break the sharp angle of said corners,

(B) rolling the edges of said strip in an approximately 90-degree V-notched roll to further shape said edges, and

(C) rolling the edges of said strip in rolls with curvilinear-bottomed grooves to fully form said edges,

(a) said grooves having a depth to width ratio of at least 2.5.

2. The method of edge-forming electrical conductor strip comprising the steps of (A) brushing the corners of said strip to deburr the same and break the sharp angle of said corners,

(B) rolling the edges of said strip in an approximately -90-degree V-notched roll to further shape said edges,

(C) rolling the edges of said strip in rolls with curvilinear-bottomed grooves to fully form said edges, said grooves having a depth to width ratio of at least 2.5, and

(D) flat rolling said strip.

3. Apparatus for edge-forming metallic strip comprising:

(A) means paying ofr" a supply of said strip,

(B) means advancing said strip through said apparatus,

(C) edge-forming rolls mounted to rotate on axes normal to the advancing of said strip,

(D) circumferential edge-forming grooves in said rolls (a) positioned to roll the edges of said strip,

(b) having a depth to width ratio of at least 2.5,

and

(c) having a Width no Igreater than about 1 mil in excess of the thickness of said strip,

(E) means mounting said rolls continuously movable with variations in the width of said strip,

(F) means urging said rolls against said strip at a pressure suicient to round the edges of said strip but insufficient -to thicken said edges, and

(G) means taking up said strip.

4. The apparatus of claim 3 wherein the urging means are air cylinders.

5. Apparatus for edge-forming metallic strip having angular corners comprising:

(A) means paying olf a supply of said strip,

(B) means advancing said strip through said apparatus,

(C) brushes mounted in the path of advance of said strip, rotating against the corners of said strip to deburr and break said corners,

(D) edge-forming rolls mounted to rotate on axes normal to the advancing of said strip,

(E) circumferential edge-forming grooves in said rolls (a) positioned to roll the edges of said strip,

(b) having a depth to width ratio'of at least 2.5,

and

(c) having a width no greater than about 1 mil in excess of the thickness of said strip,

(F) means mounting said rolls continuously movable with variations in the width of said strip,

(G) means urging said rolls against said strip at a pressure su'icient to round the edges of said strip but insuiiicient to thicken said edges, and

(H) means taking up said strip.

`6. The apparatus of claim 5 wherein said urging means are 4air cylinders.

7. Apparatus for edge-forming metallic strip having angular corners comprising:

(A) means paying olf a supply of said strip,

(B) means advancing said strip through said apparatus,

(C) brushes mounted in the path of advance of said strip rotating against the corners of said strip so as to deburr and break said corners,

(D) V-notched rolls mounted to rotate on axes normal to the advance of said strip,

(a) said rolls having circumferential V-notches positioned to engage the edges of said strip, (b) said notches further breaking said corners,

(E) edge-forming rolls mounted to rotate on axes normal to the advance of said strip,

(E) circumferential edge-forming grooves in said edgeforming rolls,

(a) positioned to roll the edges of said strip,

(b) iaving a depth to width ratio of at least 2.5,

(c) having a Width no greater than about l mil in excess of the thickness of said strip,

(G) means mounting said V-notched rolls and said edge-forming rolls continuously movable with variations in the width of said strip,

(H) means urging said V-notched rolls and said edgeforming rolls against said strip, at a pressure insuflcient to thicken said edges, and

(I) means taking up said strip.

8. The apparatus of claim 7 wherein the urging means are air cylinders.

9. An edging roll for forming the edge of metallic strip comprising:

(A) a cylindrical member rotatable about its longitudinal axis, and

(B) at least one circumferential edge-forming groove in said member,

(a) said ygroove having a substantially semicircular bottom contour, and

(b) said groove having a depth to Width ratio of at least 2.5,

(c) said groove having a width not substantially greater than 1 mil in excess of the thickness of said strip.

10. An edging roll for forming the edge of metallic strip comprising:

(A) a cylindrical member rotatable about its longitudinal axis, and (-B) at least one circumferential edge-forming groove in said member,

(a) said groove having side walls substantially straight in radial section and a curvilinear bottom contour blending into said sidewalls at circumferential lines thereon,

(b) said groove having a depth to width ratio of at least 2.5,

(c) the opening of said sidewalls not exceeding their separation at said lines by an amount exceeding about 2 mils,

(d) said groove having a width not substantially -greater than 1 mil in excess of the thickness of said strip.

' References Cited UNITED STATES PATENTS Wognum et al 72--177 CHARLES W. LANHAM, Primary Examiner. L. A. LARSON, Assistant Examiner. 

1. THE METHOD OF EDGE-FORMING ELECTRICAL CONDUCTOR STRIP COMPRISING THE STEPS OF: (A) BRUSHING THE CORNERS OF SAID STRIP TO DEBURR THE SAME AND BREAK THE SHAPE ANGLE OF SAID CORNERS, (B) ROLLING THE EDGES OF SAID STRIP IN AN APPROXIMATELY 90-DEGREE V-NOTCHED ROLL TO FURTHER SHAPE SAID EDGES, AND (C) ROLLING THE EDGES OF SAID STRIP IN ROLLS WITH CURVILINEAR-BOTTOMED GROOVES TO FULLY FORM SAID EDGES, (A) SAID GROOVES HAVING A DEPTH TO WIDTH RATIO OF AT LEAST 2.5. 